Arcuate shaped heat transfer pipes

ABSTRACT

A hot gas Stirling type engine has a heater head comprising a plurality of arcuate shaped heat transfer pipes connected between regenerator and cylinder manifolds.

United States Patent 1191 Hakansson June 18, 1974 ARCUATE SHAPED HEAT TRANSFER PIPES [56] References Cited [75] Inventor: Sven Anders Samuel Hakansson, UNITED STATES PATENTS Malmo, Sweden 2,817,950 12/1957 Van Weenem et al. 60/24 2,828,601 4 1958 M i 60 24 [73] Assignee: Kommanditbolaget United Stirling 2,963,871 12x9) :g:; 2 (S e AB & mo, 3,166,911 1/1965 Meijer 60/24 Sweden Primary Examiner-Edgar W. Geoghegan [22] Filed. Aug. 1972 Assistant Examiner-H. Burks, Sr. [21] App]. No.1 283,714 Attorney, Agent, or FirmLaurence R. Brown [30] Foreign Application Priority Data [57] ABSTPACT Au 27 197] Great Britain 40210! A hot gas St1rl1ng type engme has a heater head c0mprising a plurality of arcuate shaped heat transfer [5 2] U S C] 60/526 pipes Connected between regenerator and cylinder 51 1m. (:1. F03g 7/06 mamfolds- [58] Field of Search 60/24 2 Claims, 2 Drawing Figures This invention relates to a heater head of thekind (herein called the kind defined) provided for a hot gas engine and comprising a plurality of pipes providing connections between a high temperature working chamber and a regenerator.

The said pipes contain working gas ata high temperature and at a high pressure. They are surrounded by a flow of very hot combustion gases.

The output of the engine is dependent on the heat transfer through the walls of the pipes. Therefore it is desired that the heat-absorbing surface area should be as great as possible and the heat flux as great as possible. However, the volume of the gas in the pipes should be as small as possible as this volume is a dead" volume in the working cycle. It is also desired that the resistance against the flow of working gas through the heater head pipes should be as low as possible.

The invention is therefore intended to provide a heater head of the kind defined which is economic in manufacture and which can provide a good heatabsorbing capacity without increasing the resistance against the flow of working gas in the pipes.

According to the present invention there is provided a heater head for a hot gas engine comprising a plurality of pipes extending substantially parallel to each other between pairs of two substantially vertically extending manifolds one of which is connected to a high temperature working chamber of the engine and the other of which is connected to a regenerator of said engine, characterized in that said pipes are of arcuate shape and are disposed in the same circle as neighboring pipes extending between neighboring manifolds so as to form a vertical cylinder.

The scope of the monopoly sought is defined in the claims hereinafter, and how the invention can be put into practice is described in more detail with reference to the accompanying drawing, in which FIG. I shows schematically and partly in vertical section a heater head according to the invention with parts of a hot gas engine, and

FIG. 2 shows, to a smaller scale and viewed from above, four heater heads like that shown in FIG. 1.

Referring first to FIG. 1, a cylinder wall 1 together with a piston 2 limits a high temperature working chamber 3. A substantially vertically extending manifold 4 is secured to the top of the cylinder wall 1, and arcuate heater head pipes 5 extend horizontally and parallel to each other from the manifold 4 to a similar manifold 6 secured to the top of a regenerator 7 which inturn is mounted on a cooler 8 The cooler 8 is secured to a part 9 of the engine. In the right-hand portion of FIG. 1 another regenerator 7' and cooler 8 are shown in section. The working gas from a manifold 6' will pass through the regenerator 7' and the cooler 8' through a duct 10 to a low temperature working chamber 11 located under the piston 2. Each cooler comprises parallel pipes extending vertically and surrounded by a flow of cooling agent. Each cooler 8 or 8 is rigidly connected at its bottom to the engine part 9 but is flexible to allow sideways movements of the top of the cooler.

Such sideways movements will occur when there are changes in the temperature of the pipes 5, i.e., following starting and stopping of the engine.

As shown in FIG. 2 four cylinders l, l (and so on) and four regenerators 7, 7 are disposed in a ring as viewed from above, the pipes 5 being arcuately shaped. Thus, FIG. 2 shows four similar heater heads disposed to produce an annular formation.

It will be understood that to increase the total heatabsorbing surface area of the heater head the number of pipes 5 may be increased simply by making the manifolds 4 and 6 correspondingly taller and disposing additional pipes 5 at higher levels. This increase in heatabsorbing surface area will not increase the resistance against the flow of working gas. Also it is possible to acheive an almost uniform temperature for all the heater head pipes with small temperature differences along the pipes. The increase of dead volume is tolerable, especially when the advantage of small flow resistance is taken into account.

What is claimed is:

l. A heater head arrangement for a hot gas engine comprising in combination, a plurality of high temperature working chambers, a plurality of regenerators, said chambers and regenerators alternately disposed side by side about a circular arrangement, first manifolds extending from said chambers, second manifolds extending from said regenators, said first and second manifolds having side-by-side vertical sections, a plurality of arcuate shaped heater pipes extending between and coupled into the adjacent vertical manifold sections to connect each working chamber to a regenerator to form thereby a vertical cylindrical arrangement of said pipes.

2. An arrangement as defined in claim 1 including an engine part, and flexible means connecting said regenerators to said engine part to accommodate changes in dimension of said arcuate shaped pipes. 

1. A heater head arrangement for a hot gas engine comprising in combination, a plurality of high temperature working chambers, a plurality of regenerators, said chambers and regenerators alternately disposed side by side about a circular arrangement, first manifolds extending from said chambers, second manifolds extending from said regenators, said first and second manifolds having side-by-side vertical sections, a plurality of arcuate shaped heater pipes extending between and coupled into the adjacent vertical manifold sections to connect each working chamber to a regenerator to form thereby a vertical cylindrical arrangement of said pipes.
 2. An arrangement as defined in claim 1 including an engine part, and flexible means connecting said regenerators to said engine part to accommodate changes in dimension of said arcuate shaped pipes. 